Hydraulic drive apparatus

ABSTRACT

A plurality of hydraulic flow sources feed a plurality of hydraulic motors. A single source of mechanical power transmits power to the several hydraulic flow sources by a V-belt arrangement cooperating with the sources in such a manner that variation of length of the belt can be controlled by moving all of the hydraulic flow sources simultaneously and not with respect to each other.

United States Patent [1 1 Spinks I HYDRAULIC DRIVE APPARATUS [76] Inventor: Chester 1. Spinks, 777 Brighton,

Zanesville, Ohio 43701 [22] Filed: Mar. 23, 1972 [21] Appl. No.: 237,469

- [52] US. Cl 60/486, 60/489, ISO/6.48, 60/421, 74/2428 [51] Int. Cl. Fl5b 18/00, F16h 39/02 [58] Field-0f Search 60/489, 484, 421, 486;

. 417/362; 74/242.14 R, 242.14 B, 242.8; 37/DIG. 6, DIG. 7, DIG. 8, DIG. 17; 180/648 [56] References Cited UNITED STATES PATENTS 2,103,530 12/1937 Henry 60/421 X 2,108,738 2/1938 Allen 417/362 2,941,609 6/1960 Bowers et a1. 60/421 3,065,602 11/1962 Curlett 60/484 X 3,279,637 10/1966 Olson et a1 60/484 X 3,572,033 3/1971 Tolley 60/484 X FOREIGN PATENTS OR APPLICATIONS 193,719 3/1938 Switzerland 417/362 Primary Examiner-Edgar W. Geoghegan Attorney, Agent, or FirmI-lill, Sherman, Meroni, Gross & Simpson [5 7] ABSTRACT A plurality of hydraulic flow sources feed a plurality of hydraulic motors. A single source of mechanical power transmits power to the several hydraulic flow sources by a V-belt arrangement cooperating with the sources in such a manner that variation of length of the belt can be controlled by moving all of the-hydraulic flow sources simultaneously and not with respect to each other.

1 Claim, 3 Drawing Figures PATENTEum 1 1914 3808813 sum 1 or 2 1 HYDRAULIC DRIVE APPARATUS BACKGROUND OF THE INVENTION l. The Field of the Invention This invention relates generally to hydraulic transmissions. More specifically, this invention relates to improvements in such transmissions for tractors.

2. The Prior Art In the past, a number of tractors, often referred to in the art as loaders, have been developed. These tractors are characterized by four wheels, usually all of the same diameter, and having extremely short wheelbases. Ordinarily, a movable bucket is mounted forward of the forward wheels of such a vehicle. The engine is generally in the center or to the rear of the vehicle. A trencher or other implement may be mounted after the rear wheels of the vehicle. Generally, all of the implements attached to such a tractor or loader are hydraulically actuated. However, until the present invention, no one has developed such tractor or loader that successfully incorporates a hydraulic transmission to directly drive the wheels that engage the ground.

While loaders or tractors in the past have utilized hydraulic transmissions, there have been some drawbacks to them. For example, the Uni-Loader, marketed by the J. I. Case Company, of Racine, Wisconsin, utilizes a hydraulic transmission in driving the ground-engaging wheels of a loader. However, in this arrangement, a hydraulic transmission drives a mechanical gear transmission which in turn drives a first series of sprockets and chains to the front wheels and a second series of sprockets and chains to the rear wheels with no direct communication between either seriesof sprockets and chains other than through the output of the mechanical transmission. In this arrangement, the Uni-Loader does not achieve complete reduction through its mechanical transmission but must rely on the sprocket and chain series to obtain further reduction other than what is obtained through the mechanical geartransmission. This arrangement, while economical in some respects puts significantly increased strain on the chain and sprocket series, without providing an enclosed oil bath for all gear reduction members on the front wheels, thereby significantly increasing the probability of mechanical failure and increased maintenance cost during the operation of the vehicle.

Another device, the Warner & Swazey Duplex Beaver, which apparently has not been exploited commercially, utilizes a hydraulic transmission to transmit power to the wheels through a chain encased in oil. The means of reduction of speed of the mechanical transmission has not been disclosed in this device. However, the necessity of relying on a chain in oil increases the initial cost of the vehicle and the cost of maintenance because of requirements of changing oil and other problems common to oilsplash mechanical transmission means well known in the art.

Still another device which utilizes a hydraulic drive to wheels with a chain in oil is the Erickson Husky. In this device, a valve having a butterfly meters the transmission of hydraulic flow from a pump to hydraulic motors responsive to manual control. No means of reducing the speed of drive to the wheels nor the means of transmitting the output of the hydraulic motors to the wheels ispublicly disclosed in this device.

Still another type of loader has been developed in the past that does not utilize a hydraulic drive to power the ground-engaging wheels. A typical example of such a rior art device is that disclosed in U.S. Pat. No. 3,231,117, issued to Melroe. In this device, a mechanical drive, disc clutches, and chain drives are utilized in powering the ground-engaging wheels. One difficulty with this type of embodiment is the necessity for the driving and driven shafts to be in parallel. This necessitates a geometric arrangement of the engine in the loader with respect to the transmission that severely limits the choice of location of the engine. For example, in the specific embodiment disclosed in the aforementioned Melroe patent, it is necessary for the engine to sit low and to the rear of the vehicle and yet not obtain maximum weight distribution on the rear axle which is desirable in the operation of such a loader. By using clutches rather than hydraulic means, significant wear is obtained on an integral part of the transmission means.

SUMMARY OF THE INVENTION This invention contemplates a hydraulic transmission powered by V-belts on the engine and transmitting power to a pair of double-planetary-gear transmissions incorporated in the hubs of the forward groundengaging wheels of the vehicle. Sprockets, coaxially mounted with these wheels, and by means of an open chain that does not provide any gear reduction, thereby having less strain and not requiring any oil casing, drive a pair of rear wheels on this vehicle. Three hydraulic pumps are utilized. One pump drives hydraulically actuated implements attached to the loader. Another pair of pumps drive the right and left hydraulic transmissions. All three pumps are fixedly mounted on brackets that can be moved with respect to a driving pulley thereby selectively controlling the length of V-belts driving these pumps. Hydraulic flow is selectively controlled by manually-operated mechanical linkages'rotating a butterfly plate in a valve. This valve controls the source of hydraulic pressure in the hydraulic motors driving the planetary gears.

ON THE DRAWINGS I FIG. I is a partial transverse sectional view of the preferred embodiment of this invention;

FIG. 2 is a cross section view of the apparatus shown in FIG. 1 along the section lines II-II thereof; and

FIG. 3 is a partially broken away side view of the apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A tractor 10 is shown in side view in FIG. 3 and partial transverse sectional view'inFIG. l. The frame 12 of the tractor is supported on a pair of fore wheels 14, and a pair of aft wheels v16.

The fore wheels 14 are powered by a hydraulic motor 18 as is a rotating gear tooth member 20 fixed to the rotating axle portion 22 that rotates with a fore wheel portion 36 correspond on the starboard side to the previously mentioned hydraulic motor 18, rotating gear portion 20, rotating axle portion 22, rotating gear portion 24, and rotating axle portion 26, respectively. A pair of hydraulic conduit portions 38 and 39 conduct hydraulic fluid under pressure to the motors 18 and 28. 4

A plurality of hydraulic pumps 41, 42 and 43 pressurize hydraulic liquid and pumps 41 and 42 direct the pressurized fluid through the conduits 38 and 39. A plurality of pulleys 44,45 and 46 rotate on a corresponding plurality of shafts 47, 48 and 49 respectively. The shafts 47, 48 and 49 are input power shafts corresponding to the pumps 41, 42 and 43 respectively. Endless belts 51 and 52 impart rotation to the pulleys 44, 45 and 46 respectively. The endless belt-portions 51 and 52 are driven by a common drive pulley 54 driven by a shaft 55 powered by an engine, such as the internal combustion engine 56.

During the operation of the vehicle, theengine 56 drives the shaft 55 which results in the hydraulic fluid to circulating bi-directionally in the direction of the arrows 57 and 58, referring to the left and righthand hydraulic systems, respectively, depending on the setting of control valves 59 and 60 associated with the pumps 41 and 42 and operated by levers A and B.

' Each system includes conduit means 61 or 62 forming a closed loop circuit. The circuit 61 has the motor 18 at a point in the circuit and the pump 41 at a second point in the circuit. The circuit 62 has the motor 28 and the pump 42 at corresponding points.

A pair of mechanical levers A and B located on outboard side of pumps 41 and 42 allow the operator to control the direction and rate of flow affecting ground speed. The pump 43 provides a source of pressurized fluid to operate accessories for the tractor.

We claim as our invention:

1. In a wheeled tractor powered by hydraulic motors which in turn are driven by pumps actuated by a single prime mover, the improvement comprising an adjustable bracket mounted on the tractor, three hydraulic pumps fixedly mounted on said bracket, a drive shaft and pulley driven by said prime mover, and-mounted independently of said bracket, a driven shaft extending from each of said pumps, an endless belt engaging the pulley on said drive shaft and the pulleys of two of said pumps, a second endless belt engaging the pulley on said drive shaft, the pulley on one of said two pumps and the pulley of the third pump, whereby tension on the belts, can be adjusted without moving the pumps with respect to each other. 

1. In a wheeled tractor powered by hydraulic motors which in turn are driven by pumps actuated by a single prime mover, the improvement comprising an adjustable bracket mounted on the tractor, three hydraulic pumps fixedly mounted on said bracket, a drive shaft and pulley driven by said prime mover, and mounted independently of said bracket, a driven shaft extending from each of said pumps, an endless belt engaging the pulley on said drive shaft and the pulleys of two of said pumps, a second endless belt engaging the pulley on said drive shaft, the pulley on one of said two pumps and the pulley of the third pump, whereby tension on the belts, can be adjusted without moving the pumps with respect to each other. 